Although the apparatus according to this invention has broader applications with respect to aligning layers of continuously advancing material to form a layered assembly, it is especially useful in the production of filamentary tow for making articles such as cigarette filters. Accordingly, the invention will be described herein in that context.
In the normal process for the production of cellulose acetate cigarette filters, as described for example in British Patent 909,940, cellulose acetate is spun through a spinnerette having, for example, 100-200 orifices. The bundles of filaments or "ends" from each of a number of spinnerettes and their associated "spinning cabinets" are assembled to form a tow. This tow is normally composed of filaments of about 1.5 to about 10 denier and the denier of the tow is from about 25,000 to about 100,000. The tow is then sent to a crimping device in the form of a flat band of, for example, 4 to 10 filament-diameters thickness. The width of the tow or band may vary considerably, depending on the number of ends combined.
A typical crimper comprises a pair of nip rollers by which the tow is forced into a stuffing box against back pressure. This causes the tow to crimp.
It is, of course, highly desirable that the tow inserted in the stuffer box be of uniform cross-section. Tow which is not uniform in cross-section results in nonuniform density within the crimping chamber (stuffer box) which causes nonuniform crimp, undesirable wear on the crimper rolls and parts and can produce edge defects in the tow band.
The present invention provides apparatus for arranging the ends in an orderly or regular fashion, i.e., of rectangular cross section to overcome the difficulties of the prior art.